RAID is a technology that employs the simultaneous use of two or more hard disk drives to achieve greater levels of performance, reliability, and/or larger data volume sizes. RAID is now used as an umbrella term for computer data storage schemes that can divide and replicate data among hard disk drives. Various designs involve the design goals of increased data reliability and increased input/output performance. When several physical disks are set up to use RAID, they are said to be in a RAID array. The RAID array distributes data across several disks, but the user and operating system see the array as one single disk. RAID can be configured in various ways to serve different purposes.
RAID arrays include a RAID controller (card) that interconnects the drives in the array. Problems are often encountered regarding security for storage disks, including disks in RAID arrays, such as when disks are to be disposed of. Some useful background information is available in IBM Fortifies SMB Data, July 2008; available at: ftp://ftp.software.ibm.com/common/ssi/sa/wh/n/xsw03019usen/XSW03019USEN.PDFT, incorporated by reference here. The disks may contain data (e.g. confidential data) that should not be disposed of in a way in which access to the data by unauthorized persons is permitted. Simply stated, the task is to create, on a server that is using RAID, encrypted storage so that in the case of disposal of the drive, the data is not readable.
Existing solutions include a RAID controller with a built-in crypto engine to encrypt data that is written to and de-crypt data that is read from the RAIDed drives. For example, IBM Corporation's solution (VAULT—ServeRAID-MR10is) is a RAID SAS/SATA storage controller card that includes high-performance hardware based encryption. This solution includes expected qualities in that it provides a RAID card that enables multiple disks to be configured to provide highly available storage and it supports all major RAID levels. Notably, the solution provides an integrated encryption technology wherein the encryption/decryption is performed on the RAID controller. Significant drawbacks with such an encrypted controller are cost and introduction of a single point of failure.
As above, this conventional solution may at first seem appealing. However, this conventional solution has at least two significant issues. The first one is monetary and that is if the system is going to be encrypting all the data going to multiple drives, the encrypting (RAID) controller needs to be very fast. Phrased differently, typically in a RAID configuration, the speed of access to the data is controlled by the read-write speed of the drive. Thus, the RAID controller becomes a speed bottleneck unless considerable power is built into the chip of the encrypting RAID controller. Accordingly, this conventional solution has proven to be quite expensive (e.g., on the order of $2000).
The second problem with this conventional solution is that a reason RAIDed systems are implemented in the first place is that one wants to avoid a single point of failure (i.e., introduction of redundancy is desirable). However, employing the conventional solution introduces that single point of failure, i.e., the encrypting RAID controller. Accordingly, if the encrypting RAID controller fails, the encryption key is lost and the data on the disks becomes inaccessible even to authorized users. This is a situation to be avoided.
Existing solutions are costly since RAID controllers are often designed to be in communication with significant number of drives, such as 10 or more, and logistical considerations for encrypting/decrypting every single one of the drives can become enormous. Particularly, since RAID controllers are intended to quickly and flexibly manage access to multiple drives, the encryption hardware at the RAID controller needs to operate very quickly. In order to afford such speed and flexibility, especially in step with more and more drives assumed under control in the RAID array, tremendous costs are required to maintain the speed and nimbleness needed to preserve efficiency and avoid system slowness.
Accordingly, the inventors have recognized a need for an inexpensive and robust security arrangement for RAIDed systems.